1. Technical Field of the Invention
The present application relates to a light source discriminating apparatus that recognizes light sources detected during the hours of darkness, and to a light source discriminating program, a vehicle detection apparatus and a light control apparatus.
2. Related Art
There are known a vehicle detection apparatuses which can detect that light sources from vehicles during the hours of darkness. A type of such a vehicle detection apparatus analyzes the absolute value of the brightness of a light source. Another type of such a vehicle detection apparatus analyzes the wavelength of the light emitted from a light source. Both of these types of vehicle detection apparatus can discriminate light originating from the luminous object such as headlights of a vehicle, from light originating from a reflective object other than vehicles. For example, such vehicle detection apparatuses are disclosed in Japanese Patent Application Laid-Open Publication Nos. 2005-092857 and 2005-534903.
However, in a vehicle detection apparatus utilizing the absolute value of the brightness of a light source, the brightness of the headlights of a vehicle may coincide with the brightness of light originating from reflective objects, such as a sign, that reflect light. Thus, this type of detection apparatus has suffered from a problem that, if such coincidence occurs, a detection error may be caused, that is, light originating from an object other than vehicles may be determined as being originated from a vehicle.
Further, coincidence may also occur in a vehicle detection apparatus utilizing the wavelength of the light emitted from a light source, when it discriminates whether or not the light source is originated from a vehicle. Specifically, in such a vehicle detection apparatus, the wavelength of the reflection of the light emitted from the headlights of a vehicle may coincide with the wavelength of the light received directly from the headlights. Thus, this type of vehicle detection apparatus has also suffered from a problem of detection errors when such a coincidence occurs.